The fossil animals of the 6
to 8 million years old Baynunah Formation were deposited in a large river
system that once drained an area in the interior of the Arabian peninsula
to the northwest of modern Abu Dhabi. This river may have been part of
a larger system that includes the modern Tigris and Euphrates Rivers.
At this time sea level was substantially lower than today, and the marine
coastline was about 300 km to the east of its present location.

The Baynunah river itself had
a low gradient and was made up of numerous small channels separated by
low sand banks. The channels were probably no more than 3 meters deep,
but the entire braided river network was tens to hundreds of meters wide.
A permanent flow of water in this river is clear from the presence of
large freshwater turtles and crocodiles, including the gariel, but the
presence of catfish suggests that flow was sluggish or intermittent in
some of the channels. Occasional flow of a higher velocity is indicated
by coarser conglomerates in some of the channels and by the disarticulated
and fragmented state of some of the fossil bones.

Temperatures were warm during
Baynunah times, and calcretes preserved in the sediments indicate that
the climate was semiarid, with an annual rainfall of no more than 75 millimeters.
The vegetation consisted of a mixture of grass, shrubs, and trees, including
palm and Acacia. Trees and shrubs were probably concentrated near the
river banks, while a more open grassy vegetation grew farther away from
the river itself.

This habitat supported a rich
and diverse group of land animals, including ancient forms of elephant,
hippopotamus, horse, antelope, wolverine, hyaena, and sabre tooth cat.
Some of the animals, such as the hyaena, were twice as big as their modern
relatives. The Baynunah Formation fossils most closely resemble animals
known from this time period from North Africa, East Africa, Pakistan,
and perhaps China, while relationships with European fossil animals are
less close. This suggests that during Baynunah times animals could migrate
freely in an east-west direction, but that north-south movement may have
been restricted by barriers presented by ancient deserts, mountains, or
river systems.

Summarized from the conference
discussion of the afternoon of March 8, 1995, by Sally McBrearty.

THE
BAYNUNAH RIVER

THE
RIVER
Peter Friend (Cambridge University, UK)

All the fossils of the Baynunah
area occur in rocks that formed when a large river system flowed across
the area and deposited fine grained sands. It consisted of a belt of channels
and sand bars. The belt as a whole may have been about 1 km across, and
its channels and bars were tens to hundreds of meters across. During much
of the year flow in the main channels was low, and in some other channels
dry stretches separated more or less stagnant ponds. When floods occurred
the channels and sand bars moved, and soil pebbles and bones were eroded
out of the banks and moved into the channel beds. The bank of the channels
and the tops of some of the sand bars often became covered by grasses
and bushes, and the more stable sand bars became cemented by soil formation.
The river often flowed to the east and southeast across Abu Dhabi, although
it meandered locally.

THE
SEDIMENTS OF THE RIVER SYSTEM
Peter Ditchfield (Cambridge University, UK)

Rocks of the Baynunah Formation
have never been buried very deeply, but have been changed by contact with
ground water in the past. Microscopic and chemical analysis shows that
although rocks at the top and the bottom of the section were deposited
in a shallow sea, the middle part of the section was deposited in a large
river system with abundant vegetation on the banks. Chemical analysis
of eggshell from Miocene ostrich living near the ancient river system
indicates a mixed grass/woodland environment.

ABU
DHABI'S FOSSIL ANIMALS AND PLANTS

FOSSIL
FISH
Peter Forey (The Natural History Museum, UK)

Six to seven million years
ago the Emirate of Abu Dhabi was crossed by a slowly flowing river system
in which lived at least three kinds of fishes which fell prey to crocodiles
and scavenging carnivores. There were two species of catfishes - an airbreathing
catfish (Clarias) and Bagrus - and one species of carp-like
fish (Barbus). Air breathing catfishes may have been widespread
in Africa and Asia by this time but Bagrus moved into the area
at about the time that Afro-Arabia met Asia during continental movements.
Abu Dhabi may therefore have been an important gateway. The absence of
the hardy catfishes from the modern Arabian peninsular may suggest that
increasing aridity sterilised this part of the world and the modern carp-like
fishes living here now were reinvasions from the Horn of Africa, Asia
and the Middle East.

Three fossil turtles were found
in Abu Dhabi. One of them, a very big herbivorous and terrestrial species,
resembles the gigantic turtle living today in the semi-arid environment
of Sahel, in Africa. It also enjoys taking a bath when possible. The two
others were freshwater and carnivorous. One, a very agressive and good
swimming turtle, was the cousin of the Nile soft-shelled turtle. The second,
shy and smaller, was like the turtle living today on the border of the
Arabian Gulf.

FOSSIL
RODENTS
Hans de Bruijn (University of Utrecht, The Netherlands) and Peter Whybrow
(The Natural History Museum, UK)

The rodent fauna of the Baynunah
Formation shows strong affinities with that of the Ethiopian faunal province
and some similarity with south Adriatic assemblages, but does not show
a single genus common to faunas of a similar age in Anatolia. The Baynunah
assemblage contains a small generalized rat. This suggests that it cannot
be older than Late Turolian of the latest Miocene. One form is an entirley
new species of gerbil, which has been named Abudhabia baynunensis,
in honour of the Emirate and the region in which it occurs.

FOSSIL
ELEPHANTS
Pascal Tassy (Université P & M Curie, France)

Elephant-like remains found
at Abu Dhabi belong to three species. Two of them are well identified.
The most common is called Stegotetrabeledon syrticus, while the
rarest is a Deinotherium (only one fragment). A rare and invaluable discovery
of Stegotetrabeledon syrticus is an individual composed of skull
and lower jaw with tusks, and postcranial remains such as vertebrae, limbones
and ribs. It was found on the island of Shuwaihat. This animal was a young
adult, of about 20 to 30 years in age. The last species found at Jebel
Barakah, just one or perhaps two specimens, is an enigmatic one. We need
more discoveries for it to be identified.

Two species of primitive horses,
with three digits on each leg, are represented in Abu Dhabi. The larger
one is not yet well known. The smaller one, less than one metre high,
was probably living in open grasslands at some distance from the river
where it came to drink. It ate mostly grasses, just as modern horses do
nowadays.

Six species of antelopes, as
well as two or three species of giraffes have been found in the Baynunah
Formation, and testify to the former presence of a varied ruminant fauna
in this part of the world. They include relatives of the present day Indian
nilgai and blackbuck. However none of theses fossil animals belong to
species still alive today. Their closest relationships are to other extinct
giraffes and antelopes in North Africa and the Indian subcontinent. They
lived in a lightly wooded environment and there could not have been any
substantial development of aridity at this period. No deer were present
in the fauna.

FOSSIL
HIPPOPOTAMUS
Alan Gentry (The Natural History Museum, UK)

A species of early hippopotamus
is present in the Miocene rocks of Abu Dhabi. This animal is smaller and
more primitive than the living hippopotamus of Africa. Its most notable
feature is a mouth opening no wider than that of a modern horse or cow,
in contrast to the wide gape of the living hippopotamus. It also showed
relatively longer and more slender legs, so it would have been a more
lightly built animal. Its closest relationship is with an extinct hippopotamus
from Libya, described in 1987.

The fossil community of Abu
Dhabi includes suids, which are very interesting animals. From the seventeen
suid fossils found we can tell that there were two kinds of suids that
lived in Abu Dhabi when the Baynunah Formation was being deposited. Before
these important discoveries, we knew one of these species only from Pakistan,
and the other only from Africa. The presence of these animals confirms
that Abu Dhabi was an important and unique place where mammals from several
continents met.

FOSSIL
CARNIVORES
John Barry (Harvard University, USA)

Carnivores are the meat-eating
order of mammals. A small collection of their remains from Abu Dhabi adds
to our otherwise totally lacking knowledge of the carnivores of the Arabian
peninsular between 8 and 6 million years ago. The remains, which are all
from kinds of animals that are now extinct, includes a very large hyaena,
a second rather small hyaena, a lion-sized sabre toothed cat, and a distant
relative of the wolverines. Similar kinds of carnivores are known from
areas as distant as northern China.

Different types of plants have
distinctive carbon isotopic signatures that are retained by the soils
in which they grow and also in the teeth of animals that eat the plants.
We have retrieved these isotopic signals from ancient soils and fossil
teeth from the Baynunah Formation and used these data to reconstruct the
past vegetation. Carbon isotopes from the ancient soils indicate a grassy
woodland environment along the major river system with which they are
associated. The carbon isotopic composition of a variety of fossil herbivore
tooth enamel, including that of ancient horses, antelopes, elephants,
hippopotami, and giraffes also indicate that they fed in a mixed habitat
made up of trees, shrubs, and grass.

NEIGHBOURING
PARTS OF THE WORLD

FOSSIL
ANIMALS FROM OMAN
Herbert Thomas (Collège de France, France)

During the last ten years,
Omani-French expeditions under the aegis of the Ministry of Petroleum
and Minerals, discovered several fossil sites in the Sultanate of Oman,
in the Dhofar Province, as well as near the Oman Mountains. Although older
than the Abu Dhabi localities, the Oman discoveries indicate the existence
of a very large diversity of terrestrial mammals 30 million years ago,
comparable to those found in Abu Dhabi's western region. These faunas,
obviously with African affinities, confirms the key role of the Arabian
Peninsula in the development of Eurasian faunas at the time that Arabia
collided with Asia around 18 million years ago.

FOSSIL
FAUNAS IN AFRICA
Andrew Hill (Yale University, USA)

There are few fossiliferous
localities in Africa south of the Sahara that are the same age as the
Abu Dhabi sites. The best occur in the Tugen Hills, Kenya, where a series
of sites provide fossils ranging in age from 9 to 4 million years ago.
Over this time we can see changes in the communities of animals, resulting
in the beginnings of the characteristic modern African fauna by about
6 million years. The Red Sea has obviously limited animal movement between
sub-Saharan Africa and Arabia in the past. But it is also possible that
an early Sahara desert restricted the movement of animals between north
Africa, Arabia and Asia, and the more southern regions.

Years of research with the
Geological Survey of Pakistan have reconstructed a fossil record that
shows past links between the U.A.E. and Pakistan. Our work in northern
Pakistan rocks of Miocene age (23 to 5 million years ago) shows how the
mammal fauna developed through time, and can be used as a framework for
judging the age of the Baynunah fossils. In turn, the Baynunah fossils
shed light on Pakistani Siwalik rodents. The small mammals from the Baynunah
Formation are particularly informative because they are so diverse. The
Abu Dhabi species are similar to those from Pakistan, and they indicate
a partly moist environment. The new gerbil species Abudhabia of
U.A.E. finds a close relative in the Siwaliks, which has been named Abudhabia
pakistanensis.

OTHER
ASPECTS OF THE ABU DHABI SITES

HISTORY
OF WORK ON FOSSIL VERTEBRATES IN THE WESTERN REGION OF ABU DHABI
Andrew Hill (Yale University, USA), Peter Whybrow (The Natural History
Museum, London) and Walid Yasin (Department of Antiquities, Abu Dhabi)

The history of work on fossils
in the western region of Abu Dhabi began with the early explorations of
oil company geologists. This was followed up by Peter Whybrow (The Natural
History Museum, London) working at Jebel Barakah from 1979 onwards. In
1983 an archeological survey involving Walid Yasin of the Abu Dhabi Department
of Antiquities and a german group discovered fossils at localities further
east. These fossils and sites were examined by Andrew Hill (Yale University,
USA) in 1984 at the invitation of the Department. Whybrow, Hill and Yasin
subsequently collaborated in further research, at first funded by the
Department, and since 1991 by ADCO. Since then, other experts became involved
in investigating the fossils and associated features of the area; a region
now proving so important for understanding the geography and biology of
the Old World as a whole.

Stone tools of undoubted human
manufacture have been found at four sites on the coast of western Abu
Dhabi. While they cannot be dated precisely, their technique of manufacture
may indicate the earliest human presence that has yet been detected in
the Emirates.

Geochemical analysis of the
Miocene rocks that outcrop along the Abu Dhabi coast and on the offshore
islands, provide information on how and when these rocks were formed.
The stable isotope ratios of oxygen, carbon, sulphur and strontium preserved
in these rocks can be compared to values from around the world, to determine
how old the rocks are. They can also provide clues to the type of environment
in which they were deposited. Rocks of the Gachsaran Formation, which
occur near the city of Abu Dhabi, were deposited 19-16 million years ago
in a setting similar to the current Abu Dhabi coast, but with large saline
lakes and lagoons. Stable isotope analysis was not able to determine the
age of the fossil-bearing Baynunah Formation of western Abu Dhabi, as
these rocks have been altered over time.

THE
EXCAVATION OF THE SHUWAIHAT ELEPHANT
Peter Andrews (The Natural History Museum, UK)

The Baynunah Formation elephant
excavated in 1992-1994 at the site of Shuwaihat was found to consist of
much of the animal's head, legs, and back bone. The bones were mostly
complete, indicating absence of surface decay and carnivore action. All
of the bones were found within an area of 153 square metres, and their
scatter is due to water flow over the body. There is every indication
that the elephant died on the same spot where it was found.

THE
MAGNETISM OF THE ABU DHABI ROCKS
Ernest Hailwood (University of Southampton, UK)

The age of the rocks containing
the vertebrate fossils has been investigated by studying the magnetism
of these sediments. Rocks become magnetized parallel with the Earth's
magnetic field when they are formed and knowledge of the changes in direction
of the field with time can be used to date them. Results from the fossil-bearing
Baynunah Formation are consistent with an age of 6-8 million years. Furthermore,
the river sediments of the Baynunah Formation were laid down during a
period when the earth's magnetic field pointed on average toward the south
pole, whereas the underlying wind-blown deposits of the Shuwaihat Formation
were formed when the field pointed dominantly toward the north pole (as
at present). This indicates a significant difference in the ages of the
two formations.

THE
WORLD IN THE MIOCENE EPOCH

PAST
CLIMATES
Peter Whybrow (The Natural History Museum, UK)

Todays Old World climatic belts,
lessening rainfall from the tropics to the Equator, of which the Sahara-Sahel
belt is an example, may have been present 6 to 8 million years ago. Although
the climate far away from the river habitat of the Abu Dhabi faunas may
have been very different, it is now possible to test the idea of climatic
belts in the Old World using the new data from Abu Dhabi.

THE
WORLD'S OCEANS IN THE MIOCENE
Norman MacLeod (The Natural History Museum, UK)

Appreciation of several palaeoceanographic
factors is necessary to understand Miocene environmental and climate change.
Isolation of Antarctica (between 40 and 20 million years ago) cooled the
southern high latitudes, increased latitudinal temperature differences,
and increased seasonality world-wide. Submergence of the Iceland-Faeroe
ridge between Greenland and Europe (between 21 and 18 million years ago)
reorganised deep-water circulation in the Atlantic and caused relatively
warm water to appear off the Antarctic coast. Evaporation of this water
enhanced precipitation in the southern high latitudes and, over the course
of the Miocene, produced the Antarctic ice sheet. Development of this
ice sheet lowered sea level, increased average wind velocity, and further
increased temperature differences. Finally, isolation of the Mediterranean
Ocean Basin lowered marine salinity levels, led to increased ice production,
and lowered sea level, resulting in the temporary drying up of the Arabian
Gulf.

THE
AREA AROUND ARABIA IN THE MIOCENE
Fred Rögl (Natural History Museum, Austria)

Moving continents constantly
change the face of the Earth through geological time. The distribution
of continents and oceans, and occasional connecting landbridges between
the continents are responsible for the animal assemblages on different
areas of the Earth. The Oligocene and Miocene epochs of younger Earth
history covers the time between 34 and 5 million years before the present.
At the beginning of the Oligocene the African-Arabian continent was separated
from Eurasia. India had already crashed into Asia. Distinct faunas inhabited
the different continents. Around 18 million years ago the broad seaway
between the Mediterranean Sea and the Indian Ocean closed. The Arabian
peninsular for the first time formed a bridge between Africa and Asia.
Elephant like animals and primates moved northwards, rhinos came in from
Eurasia. Such exchanges occured repeatedly during the Miocene. Sometimes
the land bridge was blocked by short-lived marine connections between
the Indian Ocean and the Mediterranean or the Black Sea. Consequently,
the Arabian Peninsula has been the important cross-roads for faunal exchanges
between Africa and Asia, as is shown in the fossil record.